An Illinois man who claims tainted dog treats killed his Pomeranian has sued Nestle Purina and Wal-Mart for $5 million in federal court, becoming the latest dog owner to allege publicly that treats made out of chicken jerky from China have caused sickness or death.

Dennis Adkins' lawsuit suit came as Sen. Sherrod Brown, D.-Ohio, renewed his call for the Food and Drug Administration to take action against what he said was "possibly contaminated" Chinese dog treats. During a Senate hearing Thursday, Brown urged the FDA to "be as aggressive as possible to find the source of this contamination."

Adkins claims he bought "Yam Good" dog treats, made by the Waggin Train division of Nestle Purina, at an Illinois Wal-Mart on March 11, 2012 because the package advertised the contents as "wholesome, good-tasting & nutritious." Yam Good treats , manufactured in China, feature a yam center wrapped in chicken jerky.

According to Adkins, he fed his nine-year-old female Pomeranian Cleopatra one treat per day, chopped into two or three pieces, on March 13, 14 and 15. "Mr. Adkins made no other changes in her diet," alleges the complaint.

The suit also claims that Adkins did not give any of the treats to his nine-year-old male Pomeranian, Pharaoh.

On March 26, Cleopatra died of kidney failure, says Adkins. Pharaoh never got sick.

In November 2011, as Adkins notes in his complaint, the Food and Drug Administration warned that some pet owners and veterinarians were alleging that dogs who ate chicken jerky treats manufactured in China had become ill, some with kidney failure, and that some of the pets had died. The FDA's website says that consumers have alleged "vomiting, diarrhea, sometimes with blood" and "kidney problems," sometimes within hours of ingesting the products.

Adkins questioned why the Yam Good package did not make reference to the FDA warning, and instead told dog owners they should feel "confident that [they] are giving [their dogs] a wholesome treat that is both healthy and delicious." As of April 16, states the suit, the Waggin' Train website does include warnings about its products.

Adkins asks for compensatory and punitive damages, and also for an injunction against the sale of the product.

Nestle Purina has declined to comment on the litigation, but spokesperson Keith Schopp has previously told ABC News that the safety of pets is the company's utmost priority and that production of the treats in China is held to the highest quality and safety standards. "Our chicken jerky treats are safe to feed as directed," said Schopp.

Sen. Brown has been urging Congress to take the Chinese dog treat issue seriously, citing ineffective trade laws that have allowed unsafe products to slip into the U.S.

"[Pet owners] shouldn't have to worry about the safety of the food they give their pets. It's an example again of a trade issue transforming into a safety issue," Brown said on the floor of the Senate in February. "I'm calling on the FDA to accelerate its investigation of the imported pet food, especially food imported from China, where the possibility of food contamination is higher. That's the FDA's job."

On Thursday, he urged FDA chief Dr. Margaret Hamburg to "continue all efforts to find the root cause of the contaminant," according to a statement from Sen. Brown's office.

"I remain concerned about the numerous pet owners that could still be buying these treats, unaware that of the possible contamination, and feeding the treats to their beloved dogs," said Sen. Brown.

The FDA told ABC News Thursday that it is "still actively investigating the matter."

Previously, the FDA had sent a letter to Sen. Brown stating that veterinarians have tested samples and are awaiting results, but that "to date, scientists have not been able to determine a definitive cause for the reported illnesses.

The FDA issued its first warning about chicken jerky treats from China in 2007, in response to an initial wave of consumer complaints and a second in 2008. When the FDA issued a third complaint in November 2011, based on another increase in complaints, it asked consumers to report any other purported incidents directly to the agency. Since then, hundreds of dog owners have alleged that the treats have caused sickness or death in their pets.

The FDA also says on its website, "Some of the illnesses reported may be the result of causes other than eating chicken jerky."